The present invention generally relates to an electret film, and more particularly to a fluorinated cyclic olefin electret film.
Organic polymers have been known for their commercial application in making dielectric materials such as electrets. Typically, the organic polymers are made into polymer electrets by charge injection. U.S. Pat. No. 4,291,245 to Nowlin et al. disclosed polymer electrets and process for preparing the polymer electrets. The polymer electrets usually provide useful components of electrical devices, such as acoustic transducers, electrographic devices, and photocopy machines. U.S. Pat. No. 6,806,593 to Tai et al. described forming electrets from an organic polymer film. The electrets are formed by micro-machining technology in the manufacture of miniature electret microphones.
Electrets prepared by charge injection may result in a surface charge that is vulnerable to degradation by dust and humidity. The charges within the electrets may also be degraded as a result of physical vibrations or contacts with metal wires, charged bodies and conductors. A number of small, high quality, and inexpensive electret designs are currently available. However, none of the designs has been provided to minimize charge degradations for the electrets.